U.S. Secretary of State Colin Powell has reaffirmed the American commitment to a "one-China" policy and assured Beijing that the Bush administration has no "hidden agendas" with Taiwan. But in a policy seminar in Texas, Mr. Powell said the United States is concerned about a Chinese military buildup near Taiwan.

Mr. Powell irritated Chinese officials earlier this week when he shook hands with Taiwanese President Chen Shui-bian at a diplomatic reception in Panama. But in his address to the policy event at Texas A&M university, he made clear the encounter signaled no change in the "one China" policy that has prevailed since the United States switched recognition from Taiwan to Beijing more than two decades ago.

While making no direct mention of his handshake and exchange of pleasantries with Mr. Chen, the secretary said the Bush administration is sensitive to Chinese concerns on the Taiwan issue.

"We know how strongly China feels about Taiwan," acknowledged Mr. Powell. "And our abiding interest remains in the peaceful resolution of differences between China and Taiwan. President Bush has made this point many times. We have no hidden agendas here. There is no other agenda but our single policy, our one-China policy, which is clear-cut, which is principled. It has served us well for a number of decades."

Mr. Powell said the United States takes seriously its obligations under the joint communiques that formed the basis for the establishment of relations with China in 1979, and also those under the Taiwan Relations Act from Congress which provides for unofficial ties with, and sales of U.S. defensive arms to Taiwan.

Mr. Powell applauded what he said were "promising" cross-strait exchanges between China and Taiwan but also said the Chinese military buildup on the mainland opposite Taiwan "sends a very different kind of signal." He said whether China chooses peace or coercion to resolve its differences with Taiwan will "tell us a great deal" about the kind of role China seeks with its neighbors and with the United States.

Secretary Powell's address, at the George H.W. Bush Presidential Library Center, was otherwise dominated by praise for U.S.-Chinese political cooperation that has developed over the last three years during the new Bush administration.

He hailed China's role in organizing six-party talks on ending North Korea's nuclear program, its cooperation in anti-terrorism efforts, its contributions to Afghan reconstruction and support for American resolutions in the U.N. Security Council on Iraq.

At the same time, he said the United States looks for tighter controls by Beijing authorities over Chinese firms the Bush administration believes have been exporting weapons-of-mass destruction technology. He also said the United States is troubled by the imbalance, favoring China, in a bilateral trade relationship that is approaching $200 billion a year:

"We are concerned and we are still burdened by the disparity in the trade balance, by market-access problems that American manufacturers are having, and by a non-market exchange rate," said Mr. Powell. "President Bush and my good friend [Treasury] Secretary Jack Snow, and [Commerce] Secretary Evans and Trade Representative Zoellick have these points again and again to our Chinese friends in recent weeks. Our message to China is that our commercial engagement must be one that provides prosperity to both our countries."

Mr. Powell also said the United States wants to see China meet its international obligations on human rights and religious freedom, saying that only then will that country be able to "fully unleash the talents of its citizens and reach its full potential" as a member of the international community.

He acknowledged the recent release of some prominent political prisoners, but he said the United States has been disappointed by what officials say is Chinese "backsliding" on some human rights commitments to Washington.

He said the ability of U.S. and Chinese officials to speak about such issues candidly is one of the strengths of the relationship. He also said when China hosts the 2008 Olympic games, it will have a "historic opportunity" to demonstrate that it is not just becoming more prosperous and powerful but also "more just and more free."